Anodization process of long-length aluminum plate, anodization apparatus and aluminum support for planographic printing plate material

ABSTRACT

An object of the present invention is to provide a process of anodizing a long-length aluminum plate, which reduces loss of electricity. Also disclosed is an anodization process of the above plate, employing an anodization apparatus possessing an electrolyte tank, an anode, a cathode and an electric insulator with an opening forming a current flow section, the process possessing the steps of providing the plate between the cathode and the electric insulator; and anodizing the plate by supplying current between the anode and the long-length aluminum plate, wherein the opening is located at a position of at most 10% in width length from an outer side of the plate with respect to the width length of the plate, a part of the plate is brought into contact with a part of the electric insulator, and the plate and the electric insulator travel in uniform speed.

This application claims priority from Japanese Patent Application No. 2005-259086 filed on Sep. 7, 2005, which is incorporated hereinto by reference.

TECHNICAL FIELD

The present invention relates to an anodization process of forming anodzation layer on the surface of a long-length aluminum plate, an anodization apparatus used in the anodization process, and an aluminum support for a planographic printing plate material manufactured according to an anodization process.

BACKGROUND

It is well known that an aluminum plate is used as a support for a planographic printing plate material.

As the support for a planographic printing plate material is widely used an aluminum plate subjected to surface roughening treatment and anodization treatment, which provides good printing properties such as high water retention property or high printing durability.

As the anodization treatment above, there is a method in which a long length metal plate is electrolytically treated by allowing the metal plate to travel in an electrolytic solution in which an electrode is provided and supplying current between the running metal plate and the electrode facing one side of the metal plate surface, wherein an electric insulator plate is provided on the side of the metal plate opposite the electrode in the region where the electrolytic treatment is carried out (refer to Patent Document 1, for example), or a method in which an anodization layer is formed on a long-length aluminum plate in an electrolytic solution of an electrolyte tank comprising a first electrode, a second electrode and a mobile electric insulator provided between the electrodes, wherein when the aluminum plate travels between the first electrode and the electric insulator, which prevents current from flowing between the aluminum plate and the electric insulator, an anodization layer is formed only on the surface of the aluminum plate facing the first electrode, and when the aluminum plate travels between the first electrode and the electric insulator and the insulator is moved so that current flows between the aluminum plate and the second electrode, an anodization layer is formed on both surfaces of the aluminum plate (refer to Patent Document 2, for example).

Further, there is a method in which a long length sheet is provided between an anode and a cathode to form an anodization layer on the surface. For example, a method is known which employs a coil alumite one side processing apparatus employing direct current electrolysis, the apparatus comprising an electrolyte tank containing an electrolytic solution, an electricity supply electrode providing a (+) electricity and an electrolytic electrode provided with a (−) electricity each being opposed to each other in the electrolytic solution, two slit plates, a slit between the slit plates, a long-length sheet to be processed traveling between the both electrodes and then through the slit, and a U-shaped mask separator provided to cover the both edges in the transverse direction of the sheet, wherein the distance between the end on the sheet surface side of the slit plate and the sheet surface is not more than several millimeters, the distance between the wall of the U-shaped separator and the sheet surface is about 1 mm, and the distance between the wall of the U-shaped separator and the sheet end is not more than several millimeters, and wherein current for electrolysis flows in the thickness direction of the long length sheet (refer to Patent Document 3, for example).

However, these methods result in much loss of electricity, and effective anodization of an aluminum plate has been desired.

(Patent Document 1) Japanese Patent O.P.I. Publication No. 57-47894.

(Patent Document 2) Japanese Patent Examined Publication No. 63-58233.

(Patent Document 3) Japanese Patent Examined Publication No. 58-24517.

SUMMARY

It is an object of the present invention to provide a process of anodizing a long-length aluminum plate, which reduces loss of electricity, to provide an anodization apparatus used in the anodization process, and to provide a support for a printing plate material manufactured according to the anodization process.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, with reference to the accompanying drawings which are meant to be exemplary, not limiting, and wherein like elements numbered alike in several figures, in which:

FIG. 1(a) shows a side view of one embodiment in the anodization process of the present invention,

FIG. 1(b) shows a cross-sectional view of an electrolyte tank in the anodization process,

FIG. 2(a) shows the shape of the opening in the electric insulator,

FIG. 2(b) shows a cross-sectional view of the electric insulator in FIG. 2(a), and

FIG. 3 shows a side view of one example of conventional anodization apparatuses comprising an electricity supply tank.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The above object of the present invention is accomplished by the following structures.

(Structure 1) A process of anodizing a long-length aluminum plate, employing an anodization apparatus possessing an electrolyte tank charged with an electrolytic solution, and provided in the electrolytic solution, an anode, a cathode and an electric insulator with an opening that forms a current flow section, the electric insulator being provided between the anode and the cathode, the process possessing the steps of providing the long-length aluminum plate between the cathode and the electric insulator in the electrolytic solution and anodizing the long-length aluminum plate by supplying current between the anode and the long-length aluminum plate through the current flow section, whereby an anodization layer is formed on the aluminum plate surface on the side facing the cathode, wherein the opening is located at a position of at most 10% in width length from an outer side of the long-length aluminum plate with respect to the width length of the long-length aluminum plate, a part of the long-length aluminum plate is brought into contact with a part of the electric insulator, and the long-length aluminum plate and the electric insulator travel in uniform speed.

(Structure 2) The process of Structure 1, wherein the process possesses further a step of rotating the electric insulator via a plurality of rollers.

(Structure 3) The process of Structure 1, wherein the long-length aluminum plate is a support for a planographic printing plate material.

(Structure 4) The process of Structure 1, wherein a traveling speed of the long-length aluminum plate is 5-100 m/min.

(Structure 5) The process of Structure 1, wherein an amount of the anodization layer is 1.5-4 g/m².

(Structure 6) The process of Structure 1, wherein a distance between the long-length aluminum plate and the anode is 40-60 mm.

(Structure 7) The process of Structure 1, wherein a thickness of the long-length aluminum plate is 0.15-0.50 mm.

(Structure 8) An anodization apparatus possessing an electrolyte tank charged with an electrolytic solution, and provided in the electrolytic solution, an anode, a cathode, an electric insulator with an opening that forms a current flow section, the electric insulator being provided between the anode and the cathode, and a long-length aluminum plate being provided between the cathode and the electric insulator, that is anodized by supplying current between the anode and the long-length aluminum plate through the current flow section, whereby an anodization layer is formed on the aluminum plate surface on the side facing the cathode,

wherein the opening is located at a position of at most 10% in width length from an outer side of the long-length aluminum plate with respect to the width length of the long-length aluminum plate, a part of the long-length aluminum plate is brought into contact with a part of the electric insulator, and the long-length aluminum plate and the electric insulator travel in uniform speed.

While the preferred embodiments of the present invention have been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be further explained in detail. It is a feature of the present invention that a process of anodizing a long-length aluminum plate, employing an anodization apparatus comprising an electrolyte tank charged with an electrolytic solution, and provided in the electrolytic solution, an anode, a cathode and an electric insulator with an opening that forms a current flow section, the electric insulator being provided between the anode and the cathode, possesses the steps of providing the long-length aluminum plate between the cathode and the electric insulator in the electrolytic solution; and anodizing the long-length aluminum plate by supplying current between the anode and the long-length aluminum plate through the current flow section, whereby an anodization layer is formed on the aluminum plate surface on the side facing the cathode, wherein the opening is located at a position of at most 10% in width length from an outer side of the long-length aluminum plate with respect to the width length of the long-length aluminum plate, a part of the long-length aluminum plate is brought into contact with a part of the electric insulator, and the long-length aluminum plate and the electric insulator travel in uniform speed.

(Long-Length Aluminum Plate)

The aluminum plate used in the invention is a long-length aluminum plate, and materials thereof may be pure aluminum or aluminum alloy.

As the aluminum alloy, there can be used various ones including an alloy of aluminum and a metal such as silicon, copper, manganese, magnesium, chromium, zinc, lead, bismuth, nickel, titanium, sodium or iron. Further, an aluminum plate manufactured by rolling can be used.

A regenerated aluminum plate obtained by rolling aluminum regenerated from scrapped or recycled materials, which has recently spread, can be also used.

(Anodization)

Surface-roughening (graining) of a long-length aluminum plate is preferably carried out prior to anodization in the invention. It is preferable that the aluminum plate is subjected to degreasing treatment for removing rolling oil prior to surface-roughening (graining).

The degreasing treatments include degreasing treatment employing solvents such as trichlene and thinner, and an emulsion degreasing treatment employing an emulsion such as kerosene or triethanol. It is also possible to use an aqueous alkali solution such as caustic soda for the degreasing treatment. When an aqueous alkali solution such as caustic soda is used for the degreasing treatment, it is possible to remove soils and an oxidized film which can not be removed by the above-mentioned degreasing treatment alone. When an aqueous alkali solution such as caustic soda is used for the degreasing treatment, the resulting plate is preferably subjected to desmut treatment in an aqueous solution of an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid, or a mixture thereof, since smut is produced on the surface.

Subsequently, surface-roughening treatment is carried out. As the surface-roughening treatment, there are, for example, mechanical surface-roughening treatment and electrolytic surface-roughening treatment in an electrolyte solution containing hydrochloric acid or nitric acid as a main component.

Though there is no restriction for the mechanical surface-roughening method, a brushing roughening method and a honing roughening method are preferable. The brushing roughening method is carried out by rubbing the surface of the plate with a rotating brush with a brush hair with a diameter of 0.2-0.8 mm, while supplying slurry in which volcanic ash particles with a particle size of 10-100 μm are dispersed in water to the surface of the plate. The honing roughening method is carried out by ejecting obliquely slurry with pressure applied from nozzles to the surface of the plate, the slurry containing volcanic ash particles with a particle size of 10-100 μm dispersed in water. Surface-roughening can be also carried out by laminating the plate surface with a sheet on the surface of which abrading particles with a particle size of from 10 to 100 μm has been coated at intervals of 100-200 μm and at a density of 2.5×10³-10×10³/cm², and then applying pressure to the laminated sheet to transfer the roughened pattern of the sheet, whereby the plate surface is roughened.

After the plate has been roughened mechanically, it is preferably dipped in an acid or an aqueous alkali solution in order to remove abrasives and aluminum dust, etc. which have been embedded in the surface of the support. Examples of the acid include sulfuric acid, persulfuric acid, hydrofluoric acid, phosphoric acid, nitric acid and hydrochloric acid, and examples of the alkali include sodium hydroxide and potassium hydroxide. Among those mentioned above, an aqueous solution of alkali chemicals such as sodium hydroxide is preferably used. The dissolution amount of aluminum in the plate surface is preferably 0.5-5 g/m². After the plate has been dipped in the aqueous alkali solution, it is preferable for the plate to be dipped in an acid such as phosphoric acid, nitric acid, sulfuric acid and chromic acid, or in a mixed acid thereof, for neutralization.

In the electrolytic surface-roughening treatment carried out in the electrolytic solution (hereinafter also referred to as nitric acid electrolytic solution) containing nitric acid, voltage applied is generally 1-50 V, and preferably 10-30 V. The current density used can be selected from the range of 10-200 A/dm², and is preferably 20-100 A/dm². The quantity of electricity can be selected from the range of 100-2000 C/dm², and is preferably 300-1500 C/dm². The temperature during the electrolytic surface-roughening treatment may be in the range of 10-50° C., and is preferably 15-45° C. The nitric acid concentration in the nitric acid electrolytic solution is preferably 0.1-5% by weight. It is possible to optionally add, to the nitric acid electrolytic solution, nitrates, chlorides, amines, aldehydes, phosphoric acid, boric acid, acetic acid, oxalic acid or aluminum salts.

After the aluminum plate has been subjected to electrolytic surface-roughening treatment in the nitric acid electrolytic solution, it is preferably dipped in an acid or an aqueous alkali solution in order to remove aluminum dust, etc., which have been produced in the plate surface. Examples of the acid include sulfuric acid, persulfuric acid, hydrofluoric acid, phosphoric acid, nitric acid and hydrochloric acid, and examples of the alkali include sodium hydroxide and potassium hydroxide. Among those mentioned above, a phosphoric acid or sodium hydroxide aqueous solution is preferably used. The dissolution amount of aluminum in the plate surface is preferably 0.1-2 g/m² . After the plate has been dipped in the aqueous alkali solution, it is preferable for the plate to be dipped in an acid such as phosphoric acid, nitric acid and sulfuric acid, or in a mixed acid thereof, for neutralization.

In electrolytic surface-roughening treatment carried out in the electrolytic solution containing hydrochloric acid (hereinafter also referred to as hydrochloric acid electrolytic solution), the hydrochloric acid concentration in the hydrochloric acid electrolytic solution is 5-20 g/liter, and preferably 6-15 g/liter. The current density supplied is in the range of 15-200 A/dm², and preferably 20 - 150 A/dm². The quantity of electricity is in the range of 400-2000 C/dm², and preferably 500-1500 C/dm². Frequency is preferably in the range of 40-150 Hz. The temperature during the electrolytic surface-roughening treatment may be in the range of 10-50° C., and is preferably 15-45° C. It is possible to optionally add, to the hydrochloric acid electrolytic solution, nitrates, chlorides, amines, aldehydes, phosphoric acid, chromic acid, boric acid, acetic acid, oxalic acid or aluminum salts.

After the aluminum plate has been subjected to electrolytic surface-roughening treatment in the hydrochloric acid electrolytic solution, it is preferably dipped in an acid or an aqueous alkali solution in order to remove aluminum dust, etc., which have been produced in the plate surface. Examples of the acid include sulfuric acid, persulfuric acid, hydrofluoric acid, phosphoric acid, nitric acid and hydrochloric acid, and examples of the alkali include sodium hydroxide and potassium hydroxide. Among those mentioned above, a phosphoric acid or sodium hydroxide aqueous solution is preferably used. The dissolution amount of aluminum in the plate surface is preferably 0.1-2 g/m². After the plate has been dipped in the aqueous alkali solution, it is preferable for the plate to be dipped in an acid such as phosphoric acid, nitric acid, sulfuric acid and chromic acid, or in a mixed acid thereof, for neutralization.

The average surface roughness (Ra) of the surface-roughened aluminum plate is preferably 0.3-0.8 μm. The average surface roughness can be adjusted by appropriately selecting surface roughening conditions such as concentration of the electrolytic solution used, current density supplied or electricity supplied.

The anodization process of the present invention is preferably carried out after the surface-roughening treatment described above.

The anodization process of the present invention will be explained below employing figures.

FIG. 1(a) shows a side view of one embodiment in the anodization process of the present invention, and of an electrolyte tank used in EXAMPLE. FIG. 1(b) shows a cross-sectional view of FIG. 1(a) at A - A′. FIG. 2(a) is a plan view showing an example of the shape of an electric insulator, and FIG. 2(b) shows a cross-sectional view of FIG. 2(a) at B - B′. FIG. 3 shows a side view of one example of conventional anodization apparatuses including an electricity supply tank.

In FIG. 1(a), long-length aluminum plate 1 is transported in electrolyte tank 3 filled with electrolytic solution 2 via a plurality of rollers 4 to be anodized.

Long-length aluminum plate 1 travels between anode 5 and cathode 6 in electrolytic solution 2, and anode 5 and cathode 6 are placed facing to each other.

The current flow section of the present invention means the opening section provided in the area of electric insulator 8 facing long-length aluminum plate 1. In addition, fixed electric insulator 7 is placed between long-length aluminum plate 1 and anode 5.

Electric insulator 8 of the present invention in the form of an endless belt is continuously transported via a plurality of rollers 4, as shown in FIG. 1(a). Belt side 10 is closely brought into contact with fixed electric insulator 7, and convexed section 11 is also closely brought into contact with long-length aluminum plate 1. Openings produced in electric insulator 8 are served as current flow section 12.

When voltage is applied between anode 5 and cathode 6 while transporting long-length aluminum plate 1, current flows, through current flow section 12, from anode 5 to long-length aluminum plate 1, and then flows from long-length aluminum plate 1 to cathode 6, whereby an anodization layer is formed on the surface on the side facing cathode 6 of long-length aluminum plate 1. In this case, convexed section 11 of electric insulator 8 is closely brought into contact with long-length aluminum plate 1, whereby electric insulator travel 8 and long-length aluminum plate 1 travel in uniform speed. In addition, Current flow section 12 of the present invention is required to be located at a position of at most 10% in width length from an outer side of the aluminum plate with respect to the width length of the long-length aluminum plate.

Fixed electric insulator 7 contacts the wall of electrolyte tank 3. That is, the electrolytic solution on the anode side and the electrolytic solution on the cathode side combine with each other only through the current flow section.

The distance between the long-length aluminum plate and the anode is preferably 40-60 mm, in reducing loss of electric power.

In the present invention, the thickness of the long-length aluminum plate is preferably 0.15-0.5 mm. The current density to be supplied onto the surface of the long-length aluminum plate is preferably 500-10000 A/m².

The traveling speed of the long-length aluminum plate is preferably 5-100 m/min, and more preferably 10-80 m/min.

In the present invention, the shape of the current flow section, i.e., the shape of the opening in the electric insulator, may be a slit in the form of FIG. 2(a), and may also be a slit surrounded by straight lines provided in the electric insulator, a hole discontinuously provided in the electric insulator, or an opening such as holes in the network form. FIG. 2(b) also shows a cross-sectional view of the electric insulator in FIG. 2 (a). In addition, the ratio of the total opening area to the total plan view area of electric insulator 8 is designated as an opening section area ratio.

The above fixed electric insulator in the present invention refers to an insulator having a volume resistance of at least 10¹⁵ Ω. Examples thereof include a film of acryl resin, polyvinyl chloride, polypropylene, polybutylene, polyethylene, and polystyrene. Polyvinyl chloride film or polypropylene film, each having high strength, is preferably employed.

It is more effective in the present invention that plural electrolyte tanks are continuously provided.

Current density flowing through the current flow section is preferably 500-20000 A/m².

A titanium mesh or a platinum mesh can be used as material for the anode, and carbon or aluminum can be used as material for the cathode.

These need not be one body. For example, it is preferred that many anodes having a length of 50-200 mm are provided, and hydrogen gas or such does not accumulate at the cathode portion.

FIG. 3 shows a side view of one embodiment of conventional anodization apparatuses. In FIG. 3, an electricity supply tank 31 including anode 5 is provided upstream an electrolytic tank 32 including cathode 6. As anodization speed becomes high, much current is necessary where it is necessary to provide two or three power supplies separately and lengthen the cathode. However, length of anodization process is restricted as anodization speed becomes high, since an aluminum plate to be anodized works as a resistance and current may be difficult to flow.

The electrolytic solution employed in the present invention is preferably a sulfuric acid solution or an electrolytic solution containing sulfuric acid mainly (hereinafter also referred to as sulfuric acid electrolytic solution).

The content of the sulfuric acid electrolytic solution is preferably 5-50% by weight, and more preferably 15-35% by weight. The temperature of the sulfuric acid electrolytic solution is preferably 10-50° C.

Voltage applied during anodization is preferably at least 18V, and more preferably at least 20V.

The amount of the anodization layer formed on the aluminum plate is preferably 1.5-4 g/m², and more preferably 2-3 g/m².

The amount of the formed anodization layer can be obtained from the weight difference between the aluminum plates before and after dissolution of the anodization layer. The anodization layer of the aluminum plate is dissolved by being immersed at 90° C. for 5 minutes in for example, an aqueous phosphoric acid chromic acid solution, which is prepared by dissolving 35 ml of 85% by weight of phosphoric acid and 20 g of chromic acid anhydride in 1 liter of water.

Micro pores are formed in the anodization layer. The micro pore density in the anodization layer is preferably 400-700/μm², and more preferably 400-600/μm².

The aluminum plate, which has been subjected to anodization treatment, is optionally subjected to sealing treatment. For the sealing treatment, it is possible to use known methods using hot water, boiling water, steam, a sodium silicate solution, an aqueous dichromate solution, a nitrite solution, an ammonium acetate solution or polyvinyl phosphonic acid solution.

The anodization process of the invention can be carried out employing an anodization apparatus comprising the electrolyte tank as described above and a means for supplying electricity to the electrolyte tank.

In the present invention, the long-length aluminum plate is usable as a support for a planographic printing plate material, and a light sensitive planographic printing plate material can also be prepared by providing a light sensitive layer on the support for the planographic printing plate material of the present invention in which an aluminum plate has been subjected to anodization.

The light sensitive layer herein is a layer which is capable of forming an image after imagewise exposure. As such a light sensitive layer, a negative or positive working light sensitive layer, which has been used for a light sensitive layer of PS plates, can be employed.

(Positive Working Light Sensitive Layer)

As a compound used in the positive working light sensitive layer, there are o-naphthoquinonediazide compounds.

As the o-naphthoquinonediazide compound, ester of 1,2-diazonaphthoquinone sulfonic acid and pyrogallol-acetone resin is preferred which is disclosed in Japanese Patent Examined Publication No. 43-28403. Other preferred examples thereof include ester of 1,2-diazonaphthoquinone-5-sulfonic acid and phenol-formaldehyde resin as disclosed in U.S. Pat. Nos. 3,046,120 and 3,188,210, and ester of 1,2-diazonaphthoquinone-4-sulfonic acid and phenol-formaldehyde resin as disclosed in Japanese Patent O.P.I. Publication Nos. 2-96163, 2-96165, and 2-96761. As other useful o-naphthoquinonediazide compounds, there are various o-naphthoquinonediazide compounds disclosed in many patent documents, for example, in Japanese Patent O.P.I. Publication Nos. 47-5303, 48-63802, 48-63803, 48-96575, 49-38701, and 48-13854; Japanese Patent Examined Publication Nos. 37-18015, 41-11222, 45-9610, and 49-17481; U.S. Pat. Nos. 2,797,212, 3,454,400, 3,544,323, 3,573,917, 3,674,495, and 3,785,825; British Patent Nos. 1,227,602, 1,251,345, 1,267,005, and 1,329,888; and German Patent No. 854,890.

The o-quinonediazide compounds may be used alone, but is preferably used in combination with an alkali soluble resin (binder). As such an alkali soluble resin, there are novolak resins, typically, phenol-formaldehyde resin, o-, m- or p-cresol-formaldehyde resin, and phenol/cresol (o-, m- or p-cresol, or m/p- or o/m-mixed cresol)-formaldehyde resin. Other examples of the o-quinonediazide compounds include phenol-modified xylene resin, polyhydroxystyrene, poly(halogenated hydroxystyrene), and acryl resins having a hydroxyl group as disclosed in Japanese Patent O.P.I. Publication No. 51-34711.

In order to increase stability (so-called developing latitude) under various developing conditions, the positive working light sensitive layer can contain non-ionic surfactants as disclosed in Japanese Patent O.P.I. Publication Nos. 62-251740 and 2-96760 or amphoteric surfactants as disclosed in Japanese Patent O.P.I. Publication Nos. 59-121044 and 4-13149.

Examples of the non-ionic surfactants include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene sorbitan monooleate, and polyoxyethylene nonylphenyl ether. Examples of the amphoteric surfactants include alkyldi(aminoethyl)-glycine, alkylpoly(aminoethyl)glycine hydrochloride, 2-alkyl -N-carboxyethyl-N-hydroxyethylimidazolinium betaine, N -tetradecyl-N,N-betaine type compounds (for example, trade name: AMOGEN K produced by DAIICHI KOGYO CO., LTD.) and alkylimidazoline type compounds (for example, REBON 15 produced by SANYO CHEMICAL CO., LTD.). The content in the light sensitive layer of the non-ionic surfactants or amphoteric surfactants is preferably 0.05-15% by weight, and more preferably 0.1-5% by weight.

A print-out agent for obtaining a visible image immediately after imagewise exposure or a dye or pigment as an image colorant can be added into the positive working light sensitive layer.

Representative examples of the print-out agent are combinations of compounds releasing an acid on exposure (photolytically acid-releasing agent) and organic dyes capable of forming a salt. Specific examples of the combination include a combination of o-naphthoquinonediazide-4-sulfonic acid halide and a salt-forming organic dye described in Japanese Patent O.P.I. Publication Nos. 50-36209 and 53-8128, and a combination of a trihalomethyl compound and a salt-forming organic dye described in Japanese Patent O.P.I. Publication Nos. 53-36223, 54-74728, 60-3626, 61-143748, 61-151644 and 63-58440. Examples of the trihalomethyl compound include oxazole-based compounds and triazine-based compounds, and any of these is excellent in stability over time and gives a clear print-out image. As the image coloration agent, other dyes are also used other than the above-mentioned salt-forming organic dyes. Examples of the suitable dye include oil-soluble dyes and basic dyes in addition to the salt-forming organic dyes. Specific examples thereof include Oil Yellow #101, Oil Yellow #103, Oil Pink #312, Oil green BG, Oil Blue BOS, Oil Blue #603, Oil Black BY, Oil Black BS, Oil Black T-505 (all of these are manufactured by Orient Chemical Industries, Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000) and Methylene Blue (CI52015). Particularly preferable dyes are those described in Japanese Patent O.P.I. Publication No. 62-293247.

(Negative Working Light Sensitive Layer)

As the negative working light sensitive layer, there are a light sensitive layer containing a light sensitive diazo compound, a photopolymerizable light sensitive layer and a photo-crosslinking containing light sensitive layer.

As the light sensitive diazo compound is suitably used a diazo resin prepared by condensing an aromatic diazonium compound with a active carbonyl group-containing organic condensation agent, particularly aldehydes such as formaldehyde or acetaldehyde or acetals in an acidic medium. Typical examples thereof include a condensation product of p-diazophenylamine with formaldehyde. The synthetic method of these diazo resins is described in U.S. Pat. Nos. 2,679,498, 3,050,502, 3,311,605, and 3,277,074. The light sensitive diazo compound preferably is a co-condensation diazo compound comprising in the molecule an aromatic diazonium salt unit and a substituted aromatic compound unit containing no diazonium group described in Japanese Patent Examined Publication No. 49-48001, and further preferably a co-condensation diazo compound comprising in the molecule an aromatic diazonium salt unit and an aromatic compound unit having an alkali-solubilizing group such as a carboxyl group or a hydroxyl group. The light sensitive layer in the invention can contain the surfactant as denoted above in the positive working light sensitive layer in order to improve quality of the coated layer surface.

(Matting Agent)

A matting layer may be provided on the light sensitive layer in order to prevent blurring on exposure and shorten vacuum drawing time when contact exposure under vacuum is carried out.

As the light sensitive layer of the light sensitive planographic printing plate material of the present invention, a thermosensitive image formation layer can be employed which is used in a processless planographic printing plate material which requires no developing treatment.

The light sensitive planographic printing plate material comprising the support of the invention is imagewise exposed and optionally subjected to developing treatment to obtain a planographic printing plate.

EXAMPLE

Next, the present invention will be explained employing examples, but the present invention is not limited thereto. In the examples, “parts” represents “parts by weight”, unless otherwise specified.

(Preparation of Supports 1-4)

Employing a continuous aluminum plate processing apparatus as shown in FIG. 1 and additionally in FIG. 2 (a utilized apparatus is shown in FIG. 1), a 0.24 mm thick aluminum plate(according to JIS 1050) was degreased at 60° C. for 10 seconds in a 5% sodium hydroxide solution, washed with water, immersed at 25° C. for 10 seconds in a 10% nitric acid solution to neutralize, and then washed with water.

The aluminum plate was electrolytically surface-roughened at 30° C. for 10 seconds at a current density of 8 kA/m² in an aqueous solution containing 11 g/liter of hydrochloric acid, and 1.5 g/liter of dissolved aluminum, immersed in a 1% sodium hydroxide solution at 20° C. for 10 seconds, further immersed in a 10% nitric acid solution at 25° C. for 10 seconds to neutralize, and then washed with water to prepare supports 1-4. A weight of each anodization layer was 2.5 g/m². TABLE 1 Electric power Electrolyte Current consumption Support *1 *2 tank (A) *3 (kW) Remarks 1 1000 20 16000 32 512 Inv. 2 1000 40 16000 31 496 Inv. 3 1000 50 16000 30 480 Inv. 4 1000 — 16000 37 592 Comp. *1: Aluminum plate width (mm) *2: Opening section area ratio (%) *3: Electrolytic voltage (V) Inv.: Present invention Comp.: Comparative example

As is clear from Table 1, it is to be understood that the loss of electricity can be reduced employing an anodization process of the present invention, and an anodization layer can be formed on an aluminum plate.

(Preparation of Positive Working Light Sensitive Planographic Printing Plate Material)

The following positive light sensitive layer composition was coated on each of above-described supports 1 - 4 so as to give a dry coating amount of 2 g/m² to prepare a light sensitive planographic printing plate material sample.

(Positive Working Light Sensitive Layer Composition)

Esterification product (esterification rate: 20%) of a pyrogallol-acetone resin (weight average molecular weight: 2,500) with naphthoquinone(1,2) -diazide-(2)-5-sulfonylchloride   5 parts Novolak resin (weight average molecular weight:   20 parts 5,500): condensation product of mixed phenols (phenol/m-cresol/p-cresol, 5/57/38, weight ratio) and formaldehyde Esterification product(esterification rate: 50%) 0.25 parts of naphthoquinone(1,2)-diazide-(2)-5-sulfonylchloride and p-tert-octylphenol-formaldehyde novolak resin (weight average molecular weight: 1,800) 3,4-dimethoxybenzoic acid 1.25 parts 2-trichloromethyl-5-[b-(2-benzofuryl)vinyl]- 0.25 parts 1,3,4-oxadiazole Bictoria Pure Blue BOH (produced by Hodogaya 0.25 parts Kagaku Co., Ltd.) Methyl cellosolve  200 parts

The resulting light sensitive planographic printing plate material sample was imagewise exposed and developed to prepare a planographic printing plate. Employing the planographic printing plate, printing was carried out and printed matter with good image quality was obtained.

EFFECT OF THE INVENTION

The present invention is possible to provide an anodization process of a long-length aluminum plate, which reduces loss of electricity, to provide an anodization apparatus used in the anodization process, and to provide a support for a printing plate material manufactured according to the anodization process. 

1. A process of anodizing a long-length aluminum plate, employing an anodization apparatus comprising an electrolyte tank charged with an electrolytic solution, and provided in the electrolytic solution, an anode, a cathode and an electric insulator with an opening that forms a current flow section, the electric insulator being provided between the anode and the cathode, the process comprising the steps of: (a) providing the long-length aluminum plate between the cathode and the electric insulator in the electrolytic solution; and (b) anodizing the long-length aluminum plate by supplying current between the anode and the long-length aluminum plate through the current flow section, whereby an anodization layer is formed on the aluminum plate surface on the side facing the cathode, wherein the opening is located at a position of at most 10% in width length from an outer side of the long-length aluminum plate with respect to the width length of the long-length aluminum plate, a part of the long-length aluminum plate is brought into contact with a part of the electric insulator, and the long-length aluminum plate and the electric insulator travel in uniform speed.
 2. The process of claim 1, wherein the process comprises further a step of rotating the electric insulator via a plurality of rollers.
 3. The process of claim 1, wherein the long-length aluminum plate is a support for a planographic printing plate material.
 4. The process of claim 1, wherein a traveling speed of the long-length aluminum plate is 5-100 m/min.
 5. The process of claim 1, wherein an amount of the anodization layer is 1.5-4 g/m².
 6. The process of claim 1, wherein a distance between the long-length aluminum plate and the anode is 40-60 mm.
 7. The process of claim 1, wherein a thickness of the long-length aluminum plate is 0.15-0.50 mm.
 8. An anodization apparatus comprising an electrolyte tank charged with an electrolytic solution, and provided in the electrolytic solution, an anode, a cathode, an electric insulator with an opening that forms a current flow section, the electric insulator being provided between the anode and the cathode, and a long-length aluminum plate being provided between the cathode and the electric insulator, that is anodized by supplying current between the anode and the long-length aluminum plate through the current flow section, whereby an anodization layer is formed on the aluminum plate surface on the side facing the cathode, wherein the opening is located at a position of at most 10% in width length from an outer side of the long-length aluminum plate with respect to the width length of the long-length aluminum plate, a part of the long-length aluminum plate is brought into contact with a part of the electric insulator, and the long-length aluminum plate and the electric insulator travel in uniform speed. 